title: Neurovascular anatomic relationships to arthroscopic posterior and transseptal portals in different knee positions.
abstract: BACKGROUND
  No study exists that directly measures the distances between posterior portals and the popliteal artery under arthroscopic conditions.
  
  
  OBJECTIVE
  To define the anatomic relationship between the neural structures and standard posterior arthroscopic portals and between the popliteal artery and posterior as well as transseptal portals in different knee positions.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Seventeen fresh-frozen cadaveric knees were used. The posterolateral, posteromedial, and transseptal portals were established at 90° of knee flexion. The popliteal artery was revealed using a shaver placed through the posteromedial portal. The distance from those portals to the popliteal artery was measured using a precision caliper. After the measurements were made, each specimen was dissected. The distance from a needle, blade, and cannula in each portal site to the adjacent neural structures was successively measured at 30°, 90°, and 120° of knee flexion.
  
  
  RESULTS
  The mean distance (in millimeters) from the posterolateral, posteromedial, and transseptal portals to the popliteal artery was significantly smaller at 30° (32.1 ± 4.6, 36.5 ± 4.9, and 9.0 ± 3.9, respectively) than at 90° (40.7 ± 5.1, 41.0 ± 3.8, and 18.0 ± 3.8, respectively) and 120° (38.4 ± 4.8, 38.7 ± 6.0, and 21.0 ± 4.0, respectively) of knee flexion. The mean distance from the posterolateral portal to the common peroneal nerve at 90° of flexion (needle, 26.6 ± 9.5; blade, 24.7 ± 6.9; cannula, 22.1 ± 6.9) was significantly greater than the distance at 30° (needle, 23.4 ± 6.5; blade, 21.4 ± 6.4; cannula, 18.4 ± 6.3) and 120° (needle, 21.8 ± 6.6; blade, 19.1 ± 6.3; cannula, 17.4 ± 6.7) of knee flexion. The mean distance between the posteromedial portal and the inferior infrapatellar branch of the saphenous nerve at 30° (needle, 18.6 ± 4.3; blade, 15.5 ± 3.3; cannula, 13.7 ± 5.8) of flexion was smaller than at 90° (needle, 20.1 ± 6.1; blade, 16.5 ± 5.3; cannula, 14.3 ± 4.4) and 120° (needle, 21.1 ± 3.6; blade, 17.7 ± 4.9; cannula, 15.1 ± 5.9) of flexion, but there was no statistical significance. The mean distance from the posteromedial portal to the sartorial branch of the saphenous nerve at 30° (needle, 22.8 ± 6.1; blade, 19.8 ± 5.3; cannula, 17.7 ± 6.2) of flexion was significantly smaller than that at 90° (needle, 29.7 ± 3.6; blade, 26.3 ± 6.3; cannula, 23.1 ± 4.7) and 120° (needle, 31.5 ± 3.9; blade, 28.9 ± 4.1; cannula, 25.4 ± 5.1) of flexion. Conclusion/
  
  
  CONCLUSIONS
  The position of 90° of knee flexion is safe to establish posterior and transseptal arthroscopic portals. The position of 120° of knee flexion is practically safe to establish posteromedial and transseptal portals, but it is unsafe to create a posterolateral portal because the risk of damaging the common peroneal nerve is high. The position of 30° of knee flexion is not recommended to establish posterior arthroscopic portals.
authors.affiliation: Cabinet Goethe, 23 Avenue Niel, 75017 Paris, France.
authors.forename: Konstantinos G
authors.initials: KG
authors.lastname: Makridis
authors.forename: Anthony
authors.initials: A
authors.lastname: Wajsfisz
authors.forename: Nikhil
authors.initials: N
authors.lastname: Agrawal
authors.forename: Georgios
authors.initials: G
authors.lastname: Basdekis
authors.forename: Patrick
authors.initials: P
authors.lastname: Djian
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001182:Arthroscopy / Q000009:adverse effects; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000098:blood supply / Q000294:innervation / Q000601:surgery*; D007866:Leg / Q000098:blood supply / Q000294:innervation; D008297:Male; D011150:Popliteal Artery / Q000033:anatomy & histology
keywords: anatomic relationships; cadaveric study; neural structures; popliteal artery; posterior arthroscopic portals